"As you watch the season unfold, you'll realize that Raylan has met a very formidable foe, unlike any other foe he's come up against, in the past, and it makes him scratch his own head," he told Collider.

"You're also going to see Raylan in situations you've never seen him in. Justifiably so, you're going to be really upset at some things you see, coming down the pike."

Williamson added that the finale will also feature a "big showdown scene" in which "all hell breaks loose".

"I won't even tell you who's in it, but it's a hot mess," he said. "Things appear to go in one direction, and then someone makes a decision and it just changes everything and all hell breaks loose. Nobody knows who's left standing."

Asked if Limehouse will be returning for Justified's fourth season, Williamson replied: "The way we closed out this last season, which we just finished a couple weeks ago, I don't know. They leave it up in the air, which is fun. It's interesting."

Justified airs in the US Tuesday at 10pm on FX. Season three launches in the UK tomorrow (March 28) at 9pm on 5USA.